Month: November 2018

Hundreds of years ago, the only way to travel was on foot or ride on animal back or animal drawn carts. Traveling from one place to another would be taking days or weeks or may be months hence the step well (Bawari) became an important landmark site for the traveler since it had water as well as rooms/corridors to cook food and rest during the night.

Centuries ago the ground water extraction was only from open wells manually or with help of animals. Even the quantity of water withdrawal was much less than the natural recharge of rain water hence the water table was high and water was available just a few feet below the ground. In such circumstances if a big diameter well was dug to even a depth of 30 to 50 ft, it naturally got filled with water, thereafter steps were constructed from ground level till the depth of the well so that the traveler could walk down till the water level and draw water. Corridors and rooms were constructed around the water body as resting space for the travelers.

Every step well also had an open well connected to it and naturally the water level in the open well was the same as that in the step well and those travelers who had bucket etc. could draw water from the well too and even farming was done using water from these open wells.

Constructing a step well was considered a great act of charity hence step wells were constructed in large numbers not only by the ruling king as a social benefit project but also by rich traders from share of their business profits.

We observed that some step wells were ground water level dependent and were dug in alluvium and their base was permeable. Such water bodies had visible water till the ground water level was higher than the depth of the step well but as the water table declined below the base level of the step well these step wells became dry and devoid of water, as they stand today.

Some step wells were dug only till a level where natural hard rock was encountered hence these step wells have uneven hard rock non permeable base. SaraI Bawari and Kale Hanuman ki Bawari are two such historical 15th century Step wells (Bawari) at Amber, Jaipur. Restored & rejuvenated by SILVERON from 2005 and thereafter and it will be interesting to note that both these step wells hold good quantity of water even today.

To be able to do any restoration and rejuvenation work, team Silveron had to empty the water from the step well. This task was difficult since there was regular inflow of water and streams of water could be seen gushing in from the side walls at various levels from 5 to 40 ft. below the ground surface. Multiple dewatering engines were deployed day and night during the entire work to keep the water level low in order to be able to work.

These step wells are surrounded by multiple rocky hills and rain water which collects in large pockets at higher levels forms minute channels just under the surface of the ground at various levels and flows towards the step well.

As the step well fills with water, the collected water in the step well tries to go back from the same inlet points and this works as a plug to stop the in-flowing water, hence Bawari does not over flow and when water is withdrawn the same quantity is replenished.

Though the current times of fast pace travel and water supply pumped directly into the home may have made the Bawari (step well) irrelevant but they will always remain a heritage site and will continue to speaks volumes about the wisdom and caliber of our ancestors.

Team SILVERON, on the basis of their experimentation, experience and analysis conclude that for rain water harvesting, ‘diameter has very little meaning and it is the depth which is more important’.

In simple terms, since the strata keeps changing as we drill down the earth, we are likely to encounter some soil strata which absorb more water, some which absorb less and some which absorb none.

The idea of only digging a rain water collection pond for recharge purpose is partly successful since the base of the freshly dug pond will permit percolation of rain water but in due course of time it will become hard and non permeable. The diameter of the pond will increase the water holding volume of the pond but will also at the same time increase surface area from where water will evaporate. The depth of this pond may be say 5 to 10 ft so at the edges of the pond we get exposed ground strata of only 5 to 10 ft. and this is too less.

On the basis of these observations, SILVERONexcavates and develops ponds in the low lying area and simultaneously constructs recharge shafts in appropriate numbers to allow rain water to flow into the pond during rains and find passage to percolate into the ground and enrich the ground water.

Shafts in pond to recharge water and check overflowSame pond during monsoon

This makes recharge through pond a 100% successful project and SILVERON a premier solution provider for rain water harvesting.

Our knowledge about outer space is much more than our knowledge about the inside of our own earth.

Water is absorbed as soon as it is poured on the ground, so like most people, we also thought that soil and water are great friends. It was only after years of experimentation that team SILVERON realized the fact that water and soil are not friends.

We noticed that the flowing water carries suspended silt and dissolved salts from the soil and collects at the base of the low-lying area. After the collected water has evaporated the silt and salts remain deposited at the base of the low-lying area.

View of hardened non-permeable low-lying land

The repetition of this process, monsoon after monsoon gradually makes the base of the low-lying area hard and non permeable hence we observed that the soil gradually creates its own resistance to percolation of water. This is the reason for formation of water bodies in low lying areas where rain water flows and stands for months even after the monsoon.

In India these water bodies are called by different names like Nadi or Johad, etc.

View of water filled during monsoon in the same low-lying land

It is interesting to note that each time when the farmer waters his crop, the soil and water interaction leads to the same natural phenomenon of formation and deposition of film on the soil surface and this is one of the reasons why the farmer is required to till his land in order to break this film before planting the next crop. The tilling of soil is required even in potted plants as you must have observed.

Such natural phenomenons make sustainable rain water harvesting a tricky subject and hence it needs to be appreciated that though rain water harvesting may not be rocket science but it is not as simple as it appears. Investigative tools provide some help but still at the end of the day one has to execute the work in unknown terrain deep inside the ground.

Rain water harvesting is not just about digging a hole in the ground and releasing water into it. Rain water harvesting work calls for passion, imagination and experience as it is no less than doing a work of fine art.

Artificial Ground water recharge as some people prefer to address rain water harvesting as, is actually the most site specific work hence type of work and scope of work varies from location to location and the harvester who is experienced and who understands the subject has to often modify his design if he observes some new conditions even if his work in progress has reached an advanced stage since he understands that any compromise will lead to poor performance or holding of water in the structure.

Experts at SILVERON understand that earth cannot be forced to absorb water like an injection can force the antibiotic into human body hence they take all natural factors into account and design the rain water harvesting structure in accordance to the ground formation/strata of that area.This makes SILVERON a premier rain water harvesting solution provider and reflects performance of SILVERON recharge structures.

Supporting nature – a sure path to success Going against nature – a recipe for failure

Silt is the finest particles of soil which get suspended in flowing rain water and deposit at lower courses. During monsoon period the turbulence is high hence the suspended silt does not get time to settle and the water appears murky.

Suspended Silt in Rain Water

Most rain water harvesters divert all their efforts and attention on checking silt from flowing into their rain water harvesting structure. The most common focus is on construction of chamber for settlement of silt. This basically is a small underground tank where through an inlet pipe rain water with suspended silt enters and clear water is expected to go out through another outlet pipe after settlement of silt (decantation).

The rain water flowing into the silt removal chamber does not get sufficient time to stand still and let the silt settle hence most of the silt flows into the recharge structure and if at all the silt settles down in the chamber, it covers and blocks the out let which in turn starves the recharge structure of water. It is practically impossible to keep cleaning the silt chambers at regular intervals.

Silt is a natural phenomenon and should not be such a major deterrent to RWH efforts. SILVERON designs recharge shaft such that the performance is not hampered by normal silt naturally present in the flowing water. The design is such that the silt which had entered the shaft in the previous monsoon is removed easily during the pre-monsoon maintenance in subsequent year, at almost negligible cost.

Supporting nature – a sure path to success. Going against nature – a recipe for failure.

In the pursuit of designing a flawless rain water harvesting design, team SILVERON focused on choked and non functional structures to understand the reasons of failure.

It was observed that artificial ground water recharge systems designed with slotted pipe work efficiently in the first few days of rain and there after their intake efficiency reduces rapidly and finally water starts holding in them.

Slotted-pipe design based rainwater harvesting structures

Our study of the problem showed that in this structure design the rain water is directed to flow into the pipe with slots. This water fills the pipe and moves out of the slots to fill the space outside the pipe and form a water column around the pipe up to the same level as that of the column inside the pipe.

The soil particles get suspended in the water column outside & both columns recede simultaneously. The suspended silt deposits inside as well as outside the pipe, blocking the slots at the last part of the pipe. With every inflow of water, this process is repeated till all the slots in the pipe is chocked with silt and finally the pipe becomes a closed pipe – This invariably leads to system failure.

In this system, it is expected that mother earth will absorb water as soon as it comes out of the slots while ignoring the basic principle of nature that ‘water seeks it own level’ at the first opportunity.